Fuel feed for internal combustion engines



H. JUKERS FUEL FEED FOR INTERNAL COMBUSTION ENGINES Original Filed Nov.25, 1927 Sept. 3, 1935.

on ad Patented Sept. 3, 1935 PATENT OFFICE 2,012,998 4 FUEL FEED ronINTERNAL conmus'rloN ENGINES Hugo Junkers, Dessau, Germany Originalapplication November 25, 1927, Serial No. 235,703, now Patent No.1,868,636, dated July 26, 1932. Divided and this application April 10,1930, Serial No. 443,183. In Germany 6 Claims. (Cl. 123-1'40) Myinvention relates to internal combustion engines andmore especially toengines equipped t with means for varying the fuel supply and withregulating Ameans for automatically influencing the varying means insuch manner that the engine will operate at a predetermined speed, as

described in my copending application ior patent l of the United States,Serial No. 235,703, filed November 25, 1927, now Patent No. 1,868,636dated July 26, 1932, of which this application is 'a division.

As explained in this copending application, means are provided foriniluencing a regulator to adjust it for a different speed, and a memberis Y connected with the regulator which is adapted to counteract theforce acting on the movable part of the regulator. u

Any governor must regulate the speed of its engine in such manner thatthe speed is lower for full load than for no load. The maximum speedminus the minimum speed,divided bythe medium speed, is known as thepermanent variation. The permanent variation is obviously the higher,th'e larger the difference of the maximum and minimum speeds is, ascompared with thev medium speed.

If the permanent variation is high the range from maximum to' minimumspeed is high but the regulation is soft, i. e., the change from a givenamount of fuel supply to another in consequence of a change of the loadon the engine, and the corresponding variation of the speed is notabrupt but gradual. A low permanent variation, on the other hand,results in a smaller range of speeds but the regulation is more abruptbecause small speed variations cause large strokes of the governor andcorrespondingly large variations of the energy supplyto the engine.

It is an object of the present invention to obtain gradual speeding-upat lower speeds, for at these speeds only an abrupt acceleration is feltas an unpleasant jerk. To this end I provide means which are positivelyconnected with the means for adjusting the regulator and are so designedthat they vary the permanent variation inversely with the speed,adjusting the regulator for a higher permanent variation at lower speedsand for a lower permanent variation at higher speeds.

Engines of the kind described, With the speed variable within widelimits, are principally used for the propulsion Vof vehicles. In suchengines it has already been suggested to provide an automatic regulatorfor the speed which is adapted y to control the fuel measuring pump andto be adjusted forvarious speeds of the engine.

Such regulators as heretofore designed involve the drawback that whenset for a higher speed they adjust the fuel pump immediately for maximumdelivery and then regulate it back to the delivery corresponding to thenew speed. This over-regulation is particularly undesirable in vehicleengines, as the engine is speeded up quite abruptly and unpleasantjerking is brought about.

According to my invention jerking when speeded up is avoided and thechange from lower to higher speed is gradual and-imperceptible. This iseffected in the manner described by varying the permanent variation ofthe regulator inversely with the speed. A regulator with a highpermanent variation regulates gradually, as a given variation of thespeed causes a smaller variation oi the fuel delivery than with aregulator of higher permanent variation, and -thus jerking is avoided.

Y Various means may be provided for varying the permanent variation ofthe regulator, for 'instance, a spring may be provided with one of itsends attached to alever transmitting its tension to the part of theregulator which is inuenced by a change of the speed, while its otherend is adapted to be 'displaced in such manner that in the neutralposition of the movable regu- `lator part the torque exerted on the partby the' spring (being the product of spring tension and leverage) issubstantially constant for all positions of the movably end of thespring. For varying the permanent variation of the regulator the freeend o! the spring is displaced and the mechanism for displacing itisconnected to the means for adjusting the regulator, as follows: When theregulator is adjusted for a low speed the spring is substantially atright angles to the lever when the lever is in its central position. Thetorque produced by the force of the spring at the axis of the lever isabout proportional to thevariation of the force of the springand'consequently the force can vary within comparatively wide limits.The force exerted by the regulator must balance this torque and as thetorque, as mentioned, varies within such wide limits, the force exertedby the regulator'must also vary within wide limits,v and this requiresthat the speed of the engine should also vary for the correspondinglyhigh values.

The means for displacing the other end of the spring and for adjustingthe regulator for various speeds, are so connected that the 4position ofthe spring in which it is at right angles to the lever, as mentionedabove, corresponds to the adjusting of the-regulator for low speed. Whenthe Yso regulator is adjusted for high speeds the other end of thespring is displaced in such manner that. in the central position of theAlever engaged by the spring the spring is at an acute angle to thelever. In this position, the torque which the spring produces at theaxis of the lever, varies by smaller amounts for equal strokes of thelever than in the case in which the spring is' substantially at rightangles to the lever. In conformity with this, the speeds required forbalancing the torque produced by the spring in one or the other nalposition of the lever, diiler by a much smaller value than in the caseof substantially rectangular relative position of the spring and lever.

It will be understood that by providing such an additional spring at theregulator, the desired operation of the regulator is attained, i. e. thepermanent variationis high at lower and small at higher speeds.

Any kind of regulator or governor may be pro'- vided but the designbecomes partlcularly'simple if the regulator is designed so as to beinfiuenced byfthe variations of the suction at a throttling point inthev air-Supply pipe tothe engine when the speed of the engine varies.The

.suction is varied at a throttling point in the'suction pipe, forinstance, b y anormal throttle valve. A regulator orgovernor of thelast-mentioned type is equippedwith a piston or plate which reciprocatesor oscillates in a casing. 'I'he casing is connected to theatmosphere atone side of the piston and to the suction pipe at the rear of thethrottling station 'or throttling' valve at the other side oi thepiston, so that the piston is controlled by atmospheric pressure actingon one of its faces and by the suction in the suction pipe of the engineat the rear of the throttling point on its other face. This pressure isbalanced by In order to obtain a substantially higher permanentvariation for the lower ranges of speed ,marient variation is high underthese conditions. vIn the second case, with the throttle valve wide thanfor the higher ranges, -the throttle valve is connected to the other endof the spring, i. e. to the end which is not attached to the leverreferred to, in such manner that the position of its other end whicheiects a. great variation of the torque exerted by the spring,corresponds to a small free sectional area at the throttling station,and the position of the other end of the 1 spring which causes a smallvariation of the torque exerted by the spring, corresponds to the wideopen*- position of the throttle valve. In the ilrst case, with a smallfree sectional area laid open at the throttle valve and at low speed,conu siderable variation of the speed is required for balancing thetension of the spring in'the i'inal positions of the regulatorand-therefore the peropen and at high speed, the variation o! the speedrequired for balancing the tension of the spring in the nal positions ofthe regulator is much Y less so that the permanent variation is much thespring referred to. The lever to which one The piston regulates the fuelsupply to the enj gine in cooperation with thel spring, the springtending to increase the amount of fuel supplied to the engine perstroke.

smaller in the second case.

In the drawing aiiixed to this specification and forming part thereoftwo-cycle engine equipped with Vthe mechanism for varying the permanentvariation of the regulator is illustrated diagrammatically and partly insection by way of example, it being understood that the mechanism mayalso be adapted to a four-cycle engine if desired, with a diagramshowing its operation.

In the drawing and Figb2 is the diagram.

Referring now to Fig. 1, I is a two-cycle engine with a piston 2, and acrank case 3 serving as the Fig. 1 is the sectional elevation of theengine, 35

scavenging pump, 4 is the air-intake pipe of the 40 -scavenging pump I,26 is a check valve at the point where/thepipe 4 opens into the crankcase `3, 5, is a throttle in the intake pipe 4, and Il is a rodconnecting a lever on the throttle with the accelerator, or any othercontrivance, whichis 45 here shown as a pedal 3| with a pull-back springl2.

The free sectional area of the throttling point is variable. If the freesectional area is small, i. e. the throttling action is intense, aconsiderable reduction of pressure is effected already at acomparatively low speed of the engineand therefore the engine speedrequired for balancing a denite tension of the spring is comparativelylow. A small sectional area atrthe throttling point consequently isequivalent to regulation of the engine for low,speed. When the throttlevalve is opened wide, the engine must run very fast in order to producethe same reduction of pressure, or the same suction, at the rear of thethrottling point which was produced by the slowly running ,engine withthe small sectional area laid open by the throttle valve, since in orderto effect the same reduction of pressure as for the slowly runningengine, a huge amount of air -must iiow past the wide-open throttlingpoint per unit of time. 'I'he wide open position of the` throttle valveconsequently corresponds to high speed of the engine.

A regulator or governor having a piston ofthe kind referred to isadjusted for various engine speeds by the simple expedient of adjustingthe throttle valve.

By way of example, a V'regulator is illustrated 'which is iniluenced bythe pressure in the intake pipe4. A casing 8 is arranged at asuitablepoint 5U intermediate the-throttle 5 and the piston 2 of theengine I, and connected with the intake pipe 4 bya pipe I I is themovable part of the regu-l lator, in the present instance a vane oroscil-f lating piston pivoted in the casing I at I2 to rock 5i thereinwith as small a circumferential clearance as possible. The casing 8 issubdivided into two 'chambers I1 and n by 'the piston Ill, the ensmberI1 being connected with the pipe 1, and the chamber I8 being connectedto the atmosphere by an opening 9.

I 8 is a lever' which is secured on the pivot I2 outside the casing I,I4 is a connecting rod at the end of the lever I3, 23 is adouble-armedlever 6:

which is linked to the free end of the rod-I4-and at its other endqvislinked to the piston 2| of a fuel'pump 2D. 22 is a passage in the wallot the pump cylinder 2l, and21 is a fuel tank connected with thepassage. The double-armed 7i llever 23 is fulcrumed about the end'of arod 2l to which rod reciprocation is imparted through the medium of acrank, on a pulley or sprocket 28 which is actuated from a pulley orsprocket ..33 on the crank` shaft of the engine through the 71 I6. Thebell-crank lever is fulcrumed at 39 and is v connected with an arm 38 onthe acceleratori" through the medium of a rod 31.

It will be understood that the delivery of the pump 20 is varied bydisplacing the rod Il so that the time atywhich the piston 2| closestheopening 22 is advanced or retarded, varying the effective stroke of thepump and the delivery of fuel to the engine.

The operation of my mechanism is as follows:

The spring I 5 corresponds to the spring which is provided incentrifugal governors for counteracting the centrifugal force, and theoscillation of the piston II corresponds to the oscillation of the flyweights in a centrifugal governor. The force acting on the piston I I isvariable with the vacuum in the suction pipevl, and the speed of theengine is determinedby the conditions of equilibrium between Ythe forceand the reaction of the spring I5. Whenever the force andthe reactionare in equilibrium the engine runs at-a predetermined speed until theequilibrium is disturbed by a variation either of the force or of thereaction, and the engine will run at another speed at which equilibriumunder the new conditions will be re-established.

Assuming now that the free sectional area of the suction pipe 4 which islaid open by the throttle 5 is small, i. e.,`thevengine to be regulatedfor a low speed range, say, 300 to 800 revolutions per minute at lowload, the movable member or piston II descends. The free end of lever I3rises to IIa (Fig. 2). The lower `end of spring I5 is at I6, the tensionof spring I5 is F1 and its ellective arm is r1. At higher load themovable member II rises, the free end of lever I3 descends to AIIb, thelower end of spring I5 remains at I6,

thev tension of spring I5 is F2 and its effective arm is r2. In the twofinal positions illustrated in the drawing the effective arms ri and r2are equal.

When the engine is regulated for a higher speed range, say, 1450 to 1600revolutions per minute, the free sectional area laid open by thethrottle 5 is larger and the lower end oi' spring I5 is displaced to I6by the means described. At low load, with the upper end of the spring atIla, the tension of the spring is Fa and its eilective' arm is r3. Athigher load, with the upper end of the spring I5 at Hb, its tension isIF4 and its eil'ective range is greater than the difference Fa, rrandF4.

r4, for the higher speed range, but that the medium value of the tworst-mentloned,torques` Fi, r1 and Fz, rz is equal, or substantiallyequal,

to the medium value of the two last-mentionedtorques F3, ra and F4', r4.If the difference of the torques is great, asis the case for the lowerspeed range in the present instance, the variation of the speed whichcorresponds to ya given variation of the engine load, is considerable,and this means a high permanent variation. n the other hand, if thedifference of the turques is small, as is the case for the higher speedrange, the variation of the speed with the load is not as considerableas in the lower speed range, and this means a low permanent variationand so 't" regulation.

I is a spring which Under full load at'300 revs. per min., the permanentvariation is very high, being equal to For high speeds, the throttlevalve 5 is openedv wide by the pedal 3i and the end I6 of bell-cranklever 35, 36 to which the lower 4end of the spring I5 is connected, isdisplaced to I6' -by the connection 31, 33 of the bell-crank lever andthe pedal 3I, so that the axis of the spring I5 is now at an acute angleto the central position :v -:c of the piston II, its leverage is lessthan r1 in Fig. 2, and the torque of the spring I5 related to the pivotI2 is reduced. The resultant force acting on the piston II Vfrom aboveis less and so is the torque it exerts at the pivot I2 against the, alsoweaker, torque ofthe spring I5. Therefore, the weaker vacuum holds thepiston II down and the supply of fuel is a minimum. In order, however,to keep up this vacuum in the suction pipe 4 notwithstanding thewide-open throttle valve 5, the v engine must run faster.

'When the engine is now loaded with full load, it slows down and thevacuum is reduced. The fuel supply is regulated for full load and whenequilibrium has been established, the engine runs at the lowest speed ofthe high range, i. e., 1450- revs. per min. The permanent variation isvery low, being equal to l Itwill appena` that the permanent variationis high for the low, and low Vfor the high speed will occur toa personskilled in the art.

In the claims ailixed to this specification no selection of anyparticular modification of the invention is intended to the exclusion ofother modincations thereof and the right to subsequently make claim toany modification not covered by these claims is expressly reserved.

I claim:

l. In an internal combustion engine in combination, means for supplyingfuel to the engine, and means for varyingthe fuel supply to the engine.a movable member whose position is varied as 'the speed of the enginevaries, and which is .operatively connected to said supply-varyingmeans, a resilient member which is operatively connected to both saidmovable member and to said supply-varying means, and is so arranged withrespect to thesupply-varying means that its force tends toincrease thesupply of fuel, a control for varying the speed range of the engine,

and mechanism operatively connected'to said control fo varying thereaction of said resilient membe on said movable member, said mechanismbeing so designed that'the difference of the forces exerted on said`movable member by said resilient member at full and at no load isgreater for lower than for higher speed ranges'.

2. In an internal combustion engine in combination, means for supplyingfuel to the engine, and means for varying the fuel supply to the engine,a movable member whose position is varied as the speed of the enginevaries, and which is operatively connected to said supply-varying means,a spring which is attached to both said movable member and to saidsupply-varying means with one of its ends, and is so arranged withrespect to the supply-varying means that its force tends to increase thesupply of fuel, a control for varying the speed of the engine, andmechanism operatively connected to said control to which mechanism theother end of said spring is attached, for varying the position of theother end of said spring, said mechanism being so designed that thedifference of the forces exerted on said movable member by saidresilient member at full and at no load is greater for lower than forhigher speeds.

3. In an internal combustion engine in coinbination, means for supplyingfuel to the engine, and means for varying the fuel supply to the engine,a movable member whose position is varied as the speed of the enginevaries, and which is operatively connected to said supply-varying means,a control for 'varying the speed of the engine, a level which is mountedto oscillate about a fixed pivot and is operatively connected to saidmovable member, a spring which is attached to said lever at one end andis so arranged with respect to said supply-varying means that its forcetends to increase the supply of fuel, and

mechanism operatively connected to said control for displacing the otherend of said spring, said mechanism being so designed that the differenceof the forces exerted by said spring at full and at no load is greaterfor lower than for higher speeds. l

4. In an internal combustion engine, a suction pipe, means forthrottling said suction pipe, a

casing connected to said suction pipe at a point at the rear of saidthrottling means, a movable member in said casing whose position isvaried as the speed of the engine varies, means for supplying fuel tothe engine, means for varying the fuel supply, means for connecting saidmovable member to said supply-varying means, a resilient member which isoperatively connected to both said movable member and-tosaidssupply-varying means, and is so arranged with respect to the-last-mentioned means that its force tends to inpipe, means forthrottling said suction pipe, a

casing connected to said suction pipe at a point at the rear of saidthrottling means, a movable member fulcrumed in said casing, means forsupplying fuel to the engine, means for varying the fuel supply, a leveron said movable member operatively connected to said fuel varying means,a spring which is attached to said lever at one end and is soarrangedwith respect to said lever that its force tends to increase the supplyof fuel, and mechanism operatively connected to said throttling meansfor varying the reaction of said spring on said lever, said mechanismbeing so designed that the difference of the torques exerted on saidmovable member by said spring at full and at no load is greater whensaid throttling means cuts off a larger section of said suction pipe,than if it cuts 01T a smaller section'.

6. In an internal combustion engine, a suction pipe, means forthrottling said suction pipe, a casing connected to said suction pipe ata point at the rear of said throttling means, a movable member fulcrumedin said casing, means for supplying fuel to the engine, means forvarying the fuel supply, a lever on said movable member operativelyconnected to said fuel varying means, a spring which is attached to saidlever at one end and is so arranged with respect to said lever that itsforce tends to increase the supply of fuel, and an oscillating lever towhich the other end of said spring is attached, said oscillating leverbeing connected to said throttlng means in such manner that thediiferenee of the torques exerted on said movable member by said springat full and at no load is greater when said throttling means cuts of! alarger sectionof said;

suction pipe, than ifit cutsoi a smaller section.

HUGO JUNKERS.

